The annexation of Texas was a perfectly fair transaction. For nine years, since the victory of San Jacinto in 1836, Texas had been an independent republic, whose reconquest Mexico had not the slightest chance of effecting. In fact, at the very moment of annexation, the Mexican government, at the suggestion of England, had agreed to recognize the independence of Texas, on condition that the republic should not join itself to the United States. We were not taking Mexican territory, then, in annexing Texas. The new state had come into the Union claiming the Rio Grande as her southern and western boundary. By the terms of annexation all boundary disputes with Mexico were referred by Texas to the government of the United States. President Polk sent John Slidell of Louisiana to Mexico in the autumn of 1845 to adjust any differences over the Texan claims. But though Slidell labored for months to get a hearing, two successive presidents of revolution-torn Mexico refused to recognize him, and he was dismissed from the country in August, 1846.

The massing of Mexican troops on the southern bank of the Rio Grande, coupled with the refusal of the Mexican government to receive Slidell, led President Polk to order General Zachary Taylor to move to the borders. Taylor marched to the Rio Grande and fortified a position on the northern bank. The Mexican and the American troops were thus facing each other across the river. When Taylor refused to retreat to the Nueces, the Mexican commander crossed the Rio Grande, ambushed a scouting force of 63 Americans, and killed or wounded 16 of them (April 24, 1846).

When the news of the attack reached Washington early in May, Polk sent a special message to Congress, concluding with these words:

"We have tried every effort at reconciliation...But now, after reiterated menaces, Mexico has passed the boundary of the United States [the Rio Grande], has invaded our territory and shed American blood upon the American soil. She has proclaimed that hostilities have commenced, and that the two nations are at war. As war exists, and, notwithstanding all our efforts to avoid it, exists by the act of Mexico herself, we are called upon by every consideration of duty and patriotism to vindicate with decision the honor, the rights, and the interests of our country."

Meanwhile, General Taylor had driven the Mexicans back to the south bank of the Rio Grande in the battles of Palo Alto and Resaca de la Palma. Six days after the vote of Congress sanctioning the war, he crossed the Rio Grande and occupied the Mexican frontier town of Matamoros, whence he proceeded during the summer and autumn of 1846 to capture the capitals of three of the Mexican provinces.

As soon as hostilities began, Commodore Sloat, in command of our squadron in the Pacific, was ordered to seize California, and General [Stephen Watts] Kearny was sent to invade New Mexico. The occupation of California was practically undisputed. Mexico had only the faintest shadow of authority in the province, and the 6000 white inhabitants made no objection to seeing the flag of the United States raised over their forts. Kearny started with 1800 men from Fort Leavenworth, Kansas, in June, and on the eighteenth of August defeated the force of 4000 Mexicans and Indians which disputed his occupation of Santa Fé. After garrisoning this important post he detached Colonel Doliphan with 850 men to march through the northern provinces of Mexico and effect a juncture with General Taylor at Monterey, while he himself with only 100 men continued his long journey of 1500 miles to San Diego, California, where he joined Sloat's successor, Stockton.

After these decided victories and uninterrupted marches of Taylor, Kearny, Sloat, Stockton, and Doniphan, the Mexican government was offered a fair chance to treat for peace, which it refused. Then President Polk decided, with the unanimous consent of his cabinet, to strike at the heart of Mexico. General Winfield Scott, a hero of the War of 1812, was put in command of an army of about 12,000 men, to land at Vera Cruz and fight his way up the mountains to the capital city of Mexico. Santa Anna, who, by the rapid shift of revolutions, was again dictator in Mexico, heard of this plan to attack the capital and hastened north with 20,000 troops to surprise and destroy Taylor's army before Scott should have time to take Vera Cruz. But Taylor, with an army one-fourth the size of Santa Anna's, drove the Mexicans back in the hotly contested battle of Buena Vista (February 23, 1847), securing the Californian and New Mexican conquests. Santa Anna hastened southward to the defense of the city of Mexico.

Scott took Vera Cruz in March and worked his way slowly but surely, against forces always superior to his own, up to the very gates of Mexico (August, 1847). Here he paused, by the President's orders, to allow the Mexicans another chance to accept the terms of peace which the United States offered,-the cession by Mexico of New Mexico and California in return for a large payment of money. The Mexican commissioners, however, insisted on having both banks of the Rio Grande and all of California up to the neighborhood of San Francisco, besides receiving damages for injuries inflicted by the American troops in their invasions. These claims were preposterous, coming from a conquered country, and there was nothing left for Scott to do but to resume military operations. Santa Anna defended the capital with a force of 30,000 men, but the Mexicans were no match for the American soldiers. Scott stormed the fortified hill of Chapultepec and advanced to the gates of the city. On the thirteenth of September his troops entered the Mexican capital and raised the Stars and Strips over "the palace of the Montezumas."

From the beginning of the war Polk had been negotiating for peace. He had kept Slidell in Mexico long after the opening of hostilities and had sent Nicholas Trist as special peace commissioner to join Scott's army at Vera Cruz and to offer Mexico terms of peace at the earliest possible moment. He had allowed Santa Anna to return to Mexico from his exile in Cuba in the summer of 1846, because the wily and treacherous dictator held out false promises of effecting a reconciliation between Mexico and the United States. He had asked Congress for an appropriation of $2,000,000 for peace negotiations when General Taylor was still near the Rio Grande, ten days before General Kearny had taken Santa Fé and the province of New Mexico, and before General Scott's campaign had been thought of.

When the Mexican commissioners made advances for peace at the beginning of the year 1848, they were given terms almost as liberal as those offered them before Scott had stormed and occupied their capital. By the treaty concluded at Guadalupe-Hidalgo, February 2, 1848, Mexico was required to cede California and New Mexico to the United States and to recognize the Rio Grande as the southern and western boundary of Texas. In return, the United States paid Mexico $15,000,000 cash and assumed some $3,250,000 more in claims of American citizens on the Mexican government. Considering the facts that California was scarcely under Mexican control at all and might have been taken at any moment by Great Britain, France, or Russia; that New Mexico was still the almost undisturbed home of Indian tribes; that the land from the Nueces to the Rio Grande was almost a desert; and that the American troops were in possession of the Mexican capital, the terms offered Mexico were very generous. Polk was urged by many to annex the whole country of Mexico to the United States, but he refused to consider such a proposal.

The Mexican War has generally been condemned by American historians as "the foulest blot on our national honor," a war forced upon Mexico by slaveholders greedy for new territory, a perfect illustration of La Fontaine's fable of the wolf picking a quarrel with the lamb solely for an excuse to devour him. But Mexico had insulted our flag, plundered our commerce, imprisoned our citizens, lied to our representatives, and spurned our envoys. As early as 1837 President Jackson said that Mexico's offenses "would justify in the eyes of all nations immediate war." To be sure we were a strong nation and Mexico a weak one. But weakness should not give immunity to continued and open insolence. We had a right to annex Texas after that republic had maintained its independence for nine years; yet Mexico made annexation a cause of war. We were willing to discuss the boundaries of Texas with Mexico; but our accredited envoy was rejected by two successive Mexican presidents, who were afraid to oppose the war spirit of their country. We even refrained from taking Texas into the Union until Great Britain had interfered so far as to persuade Mexico to recognize the independence of Texas if she would refuse to join the United States.

If there was anything disgraceful in the expansionist program of the decade 1840-1850, it was not the Mexican War, but the annexation of Texas. The position of the abolitionists on this question was clear and logical. They condemned the annexation of Texas as a wicked extension of the slavery area, notwithstanding all arguments about "fulfilling our manifest destiny" or "attaining our natural boundaries." To annex Texas might be legally right, they said, but it was morally wrong. James Russell Lowell, in his magnificent poem "The Present Crisis" (1844), warned the annexationists that "They enslave their children's children who make compromise with sin." We certainly assumed a great moral responsibility when we annexed Texas. However, it was not to Mexico that we were answerable, but to the enlightened conscience of the nation.

With our acquisition of the Oregon territory to the forty-ninth parallel by the treaty of 1846 with Great Britain, and the cession of California and New Mexico by the treaty of Guadalupe-Hidalgo in 1848, the boundaries of the United States reached practically their present limits. The work of westward extension was done. Expansion, the watchword of the decade 1840-1850, was dropped from our vocabulary for fifty years, and the immense energies of the nation were directed toward finding a plan on which the new territory could be organized in harmony with the conflicting interests of the free and slave sections of our country.